ANALYSIS AND DE-NOISING OF PARTIAL DISCHARGE SIGNALS IN MEDIUM VOLTAGE XLPE CABLES

The partial discharge (PD) measurements have been widely used in the field of insulation diagnostics . The presence of partial discharges inside the cable indicates the degradation of insulation material . This paper deals with the development of insulation diagnostic method based on the partial discharge measurements . The useful information about the partial discharge activity and insulation defects is extracted by the experimental results . A measuring test setup was established in the high voltage laboratory . Artificial cavity was introduced inside the MV XLPE cable by using the traditional needleplane configuration . The aim of study was to interpret the variations in the partial discharge characteristics over the insulation ageing period in terms of physical phenomenon’s taking place in PD sources . The statistical characteristics formulated with the help of PRPDA technique and characteristics by using HFCT sensor were studied and analyzed . The variations in these characteristics allow to diagnose the insulation conditions as well as detect the type of discharge mechanisms . In order to design an efficient de-noising filter for onsite and online PD monitoring system . various factors such as optimal wavelet selection, number of decomposition levels and threshold setting has been studied . An automated de-noising based on the frequency characteristics of partial discharge signals has been presented in this study .

Keywords:

Partial Discharge characteristics , XLPE insulated cables , insulation degradation , monitoring , PRPDA